Water quality monitoring in coastal areas using satellite imagery

The implementation of water quality European Water Framework (WFD) and Marine Strategy Directives (MSFD) requires an intensification of water quality monitoring, with-in the limits of the Exclusive Economic Zone. Remote sensing technologies can provide a valuable tool for frequent, synoptic, water-quality observations, over large areas. Hence, ocean colour data is used increasingly as a tool to assess water quality, by estimating the concentration of the water constituents, such as chlorophyll-a (a proxy of the eutrophication risk). Both MODIS and MERIS, the satellite sensors selected for this study, provide global and daily ocean information and satellite-derived chlorophyll-a maps at a medium resolution. However, algorithms designed for assessments at global scales for these sensors are less accurate locally, due to the variability of optically-active in-water constituents. Hence, regionally parameterized empirical algorithms are useful to cope with the inaccuracies produced. Additionally, to improve the water quality assessment in Basque coastal waters, the effect of river discharges needs to be studied.